A novel seven-octapeptide repeat insertion in the prion protein gene (PRNP) in a Dutch pedigree with Gerstmann-Sträussler-Scheinker disease phenotype: comparison with similar cases from the literature

Pooled analysis of patients with inherited prion disease caused by two- to twelve-octapeptide repeat insertions in the prion protein gene (PRNP)

Inherited prion diseases caused by two- to twelve-octapeptide repeat insertions (OPRIs) in the prion protein gene (PRNP) show significant clinical heterogeneity. This study describes a family with two new cases with a 4-OPRI mutation and two asymptomatic mutation carriers. The pooled analysis summarizes all cases reported in the literature to date and describes the relation between survival, age of onset, number of OPRI and codon 129 polymorphism. MEDLINE and Google Scholar were queried from database inception up to December 31, 2022. Age of onset was compared per number of OPRI and per codon 129 polymorphism using the Kruskal-Wallis and Wilcoxon-Mann-Whitney tests, respectively. Disease duration was modeled non-parametrically by a Kaplan-Meier model and semi-parametrically by a Cox model. This study comprised 164 patients. Lower number of OPRI and presence of valine (cis-V) versus methionine (cis-M) on codon 129 were associated with an older age of onset (P < 0.001 and P = 0.025, respectively) and shorter disease duration (P < 0.001 and P = 0.003, respectively). Within patients with 5- or more OPRI codon cis-V remained significantly associated with a shorter disease duration. Codon 129 homozygosity versus heterozygosity was not significantly associated with age of onset or disease duration (P = 0.076 and P = 0.409, respectively). This study summarized the largest cohort of patients with two- to twelve-OPRI to date. Lower number of OPRI and codon 129 cis-V is associated with an older age of onset and shorter disease duration, while homozygosity or heterozygosity on codon 129 was not.

Human prion diseases and the prion protein - what is the current state of knowledge?

Prion diseases and the prion protein are only partially understood so far in many aspects. This explains the continued research on this topic, calling for an overview on the current state of knowledge. The main objective of the present review article is to provide a comprehensive up-to-date presentation of all major features of human prion diseases bridging the gap between basic research and clinical aspects. Starting with the prion protein, current insights concerning its physiological functions and the process of pathological conversion will be highlighted. Diagnostic, molecular, and clinical aspects of all human prion diseases will be discussed, including information concerning rare diseases like prion-associated amyloidoses and Huntington disease-like 1, as well as the question about a potential human threat due to the transmission of prions from prion diseases of other species such as chronic wasting disease. Finally, recent attempts to develop future therapeutic strategies will be addressed.

Amino Acid Substitution within Seven-Octapeptide Repeat Insertions in the Prion Protein Gene Associated with Short-Term Course

The majority of seven-octapeptide repeat insertion (7-OPRI) carriers exhibit relatively early onset and a slowly progressive course. We have presented three cases of 7-OPRI, including two that are rapidly progressing, and compared the clinical and ancillary characteristics of the short-term and long-term disease course, as well as factors that influence disease course. The clinical and ancillary features of three new 7-OPRI patients in a Chinese pedigree were analyzed. Global data on 7-OPRI cases were then collected by reviewing the literature, and the cases were grouped according to clinical duration as per the WHO sCJD criteria, with a two-year cut-off. A Chinese pedigree has a glycine-to-glutamate substitution within the 7-OPRI insertion, which enhances the hydrophilicity of the prion protein. Two cases in this pedigree had a short disease course (consistent with the typical clinical and ancillary features of sCJD). In addition, the members of this pedigree had a later onset (p < 0.001) and shorter disease course (p < 0.001) compared to previously reported 7-OPRI cases with 129 cis-M and a similar age of onset and disease course to that of cases with 129 cis-V. The 7-OPRI cases with a shorter clinical course (n = 4) had a later onset (p = 0.021), higher rate of hyperintensity on MRI (p = 0.029) and higher frequency of 129 cis-V (p = 0.066) compared to those with a longer clinical course (n = 13). The clinical presentation of 7-OPRI is significantly heterogeneous. Codon 129 cis-V and amino acid substitution within repeat insertions are possible contributors to the short-term disease course of 7-OPRI.

Human Prion Disorders: Review of the Current Literature and a Twenty-Year Experience of the National Surveillance Center in the Czech Republic

Human prion disorders (transmissible spongiform encephalopathies, TSEs) are unique, progressive, and fatal neurodegenerative diseases caused by aggregation of misfolded prion protein in neuronal tissue. Due to the potential transmission, human TSEs are under active surveillance in a majority of countries; in the Czech Republic data are centralized at the National surveillance center (NRL) which has a clinical and a neuropathological subdivision. The aim of our article is to review current knowledge about human TSEs and summarize the experience of active surveillance of human prion diseases in the Czech Republic during the last 20 years. Possible or probable TSEs undergo a mandatory autopsy using a standardized protocol. From 2001 to 2020, 305 cases of sporadic and genetic TSEs including 8 rare cases of Gerstmann-Sträussler-Scheinker syndrome (GSS) were confirmed. Additionally, in the Czech Republic, brain samples from all corneal donors have been tested by the NRL immunology laboratory to increase the safety of corneal transplants since January 2007. All tested 6590 corneal donor brain tissue samples were negative for prion protein deposits. Moreover, the routine use of diagnostic criteria including biomarkers are robust enough, and not even the COVID-19 pandemic has negatively impacted TSEs surveillance in the Czech Republic.

[Inherited Creutzfeldt-Jakob disease with four-octapeptide repeat insertional mutation in the prion gene]

We report a case of a 60-year-old man who presented with symptoms of memory loss, gait disorder, and sluggish movement. We considered both Parkinson's disease and multiple system atrophy as possible diagnoses and consequently hospitalized the patient owing to the worsening symptoms and the development of consciousness disorder. During the course of the disease, dementia, loss of consciousness, and movement disorders worsened rapidly within one year after admission, and the patient eventually developed mutism. The significant clinical characteristics of our case included no myoclonus and involuntary tremors in the extremities. There was no periodic synchronous discharge on electro-encephalography and cranial MRI with diffusion-weighted images showed no high-intensity findings in cortex. Prion protein genetic analysis identified four repeated insertional mutations in the octapeptide repeat (OPR) region, and the patient was diagnosed with inherited Creutzfeldt-Jakob disease. Cases of OPR insertional mutations are a few in Japan and occur in about 10% of population in Europe. Creutzfeldt-Jakob disease with OPR insertional mutation shows various clinical manifestations and atypical findings on electroencephalography and cranial MRI. Diagnosing for Creutzfeldt-Jakob disease with OPR insertional mutation is important in Prion protein genetic analysis.

Case Report: Histopathology and Prion Protein Molecular Properties in Inherited Prion Disease With a De Novo Seven-Octapeptide Repeat Insertion

The insertion of additional 168 base pair containing seven octapeptide repeats in the prion protein (PrP) gene region spanning residues 51–91 is associated with inherited prion disease. In 2008, we reported the clinical features of a novel de novo seven-octapeptide repeat insertion (7-OPRI) mutation coupled with codon 129 methionine (M) homozygosity in the PrP gene of a 19-year-old man presenting with psychosis and atypical dementia, and 16-year survival. Here, we describe the histopathological and PrP molecular properties in the autopsied brain of this patient. Histopathological examination revealed widespread brain atrophy, focal spongiform degeneration (SD), cortical PrP plaques, and elongated PrP formations in the cerebellum. Overall, these histopathological features resemble those described in a Belgian pedigree with 7-OPRI mutation except for the presence of PrP plaques in our case, which are morphologically different from the multicore plaques described in some OPRI mutations and in Gerstmann–Sträussler–Scheinker (GSS) syndrome. The comparative characterization of the detergent-soluble and detergent-insoluble PrP in our patient and in sporadic Creutzfeldt–Jakob disease (CJD) revealed distinct molecular signatures. Proteinase K digestion of the pathogenic, disease-associated PrP (PrP^D) revealed PrP^D type 1 in the cerebral cortex and mixed PrP^D types 1 and 2 in the cerebellum. Altogether, the present study outlines the importance of assessing the phenotypical and PrP biochemical properties of these rare conditions, thereby widening the spectrum of the phenotypic heterogeneity of the 7-OPRI insertion mutations. Further studies are needed to determine whether distinct conformers of PrP^D are associated with two major clinico-histopathological phenotypes in prion disease with 7-OPRI.

A Novel Eight Octapeptide Repeat Insertion in PRNP Causing Prion Disease in a Danish Family

Octapeptide repeat insertions (OPRI) found in the prion protein gene (PRNP) constitute a subgroup of pathogenic mutations linked to inherited prion diseases, a hallmark of which is a misfolded prion protein. The number of repeats in OPRI has been associated with different disease phenotypes. However, due to the rarity of the cases and heterogenous disease manifestations, the recognition and classification of these variants has been difficult. Here, we report the first Danish family, the fifth worldwide, carrying a novel 8-OPRI with a unique sequence of the additional 8 inserts: R1-R2-R2-R3-R2-R2-R2a-R2-R3g-R2-R2-R3-R4. The mutation was found on the allele coding for methionine at codon 129 in the PRNP gene. The clinical exome sequencing revealed that no other dementia-associated genes harbored pathogenic alterations. Mutation carriers had onset of symptoms in their early thirties, but disease duration varied from 5 to 11 years. Progressive dementia with psychiatric and motor symptoms were the most prominent clinical features. Clinical, pathological, and genetic characteristics of other 4 reported families with 8-OPRI were reviewed and compared with the findings in the Danish family.

Genetic PrP Prion Diseases

Genetic prion diseases (gPrDs) caused by mutations in the prion protein gene (PRNP) have been classified as genetic Creutzfeldt-Jakob disease, Gerstmann-Sträussler-Scheinker disease, or fatal familial insomnia. Mutations in PRNP can be missense, nonsense, and/or octapeptide repeat insertions or, possibly, deletions. These mutations can produce diverse clinical features. They may also show varying ancillary testing results and neuropathological findings. Although the majority of gPrDs have a rapid progression with a short survival time of a few months, many also present as ataxic or parkinsonian disorders, which have a slower decline over a few to several years. A few very rare mutations manifest as neuropsychiatric disorders, with systemic symptoms that include gastrointestinal disorders and neuropathy; these forms can progress over years to decades. In this review, we classify gPrDs as rapid, slow, or mixed types based on their typical rate of progression and duration, and we review the broad spectrum of phenotypes manifested by these diseases.

Genetic PrP Prion Diseases

Genetic prion diseases (gPrDs) caused by mutations in the prion protein gene (PRNP) have been classified as genetic Creutzfeldt-Jakob disease, Gerstmann-Sträussler-Scheinker disease, or fatal familial insomnia. Mutations in PRNP can be missense, nonsense, and/or octapeptide repeat insertions or, possibly, deletions. These mutations can produce diverse clinical features. They may also show varying ancillary testing results and neuropathological findings. Although the majority of gPrDs have a rapid progression with a short survival time of a few months, many also present as ataxic or parkinsonian disorders, which have a slower decline over a few to several years. A few very rare mutations manifest as neuropsychiatric disorders, with systemic symptoms that include gastrointestinal disorders and neuropathy; these forms can progress over years to decades. In this review, we classify gPrDs as rapid, slow, or mixed types based on their typical rate of progression and duration, and we review the broad spectrum of phenotypes manifested by these diseases.

Genetic Creutzfeldt-Jakob disease

Genetic Creutzfeldt-Jakob disease (CJD) is associated with mutations in the human PrP gene (PRNP) on chromosome 20p12-pter. Pathogenic mutations have been identified in 10-15% of all CJD patients, who often have a family history of autosomal-dominant pattern of inheritance and variable penetrance. However, the use of genetic tests implemented by surveillance networks all over the world increasingly identifies unexpectedly PRNP mutations in persons apparently presenting with a sporadic form of CJD. A high phenotypic variability was reported in genetic prion diseases, which partly overlap with the features of sporadic CJD. Here we review recent advances on the epidemiologic, clinical, and neuropathologic features of cases that phenotypically resemble CJD linked to point and insert mutations of the PRNP gene. Multidisciplinary studies are still required to understand the phenotypic spectrum, penetrance, and significance of PRNP mutations.

Dominantly inherited prion protein cerebral amyloidoses - a modern view of Gerstmann-Sträussler-Scheinker

Among genetically determined neurodegenerative diseases, the dominantly inherited prion protein cerebral amyloidoses are characterized by deposition of amyloid in cerebral parenchyma or blood vessels. Among them, Gerstmann-Sträussler-Scheinker disease has been the first to be described. Their clinical, neuropathologic, and molecular phenotypes are distinct from those observed in Creutzfeldt-Jakob disease (CJD) and related spongiform encephalopathies. It is not understood why specific mutations in the prion protein gene (PRNP) cause cerebral amyloidosis and others cause CJD. A significant neurobiologic event in these amyloidoses is the frequent coexistence of prion amyloid with tau neurofibrillary pathology, a phenomenon suggesting that similar pathogenetic mechanisms may be shared among different diseases in the sequence of events occurring in the cascade from amyloid formation to tau aggregation. This chapter describes the clinical, neuropathologic, and biochemical phenotypes associated with each of the PRNP mutations causing an inherited cerebral amyloidosis and emphasizes the variability of phenotypes.

Prion disease: experimental models and reality

The understanding of the pathogenesis and mechanisms of diseases requires a multidisciplinary approach, involving clinical observation, correlation to pathological processes, and modelling of disease mechanisms. It is an inherent challenge, and arguably impossible to generate model systems that can faithfully recapitulate all aspects of human disease. It is, therefore, important to be aware of the potentials and also the limitations of specific model systems. Model systems are usually designed to recapitulate only specific aspects of the disease, such as a pathological phenotype, a pathomechanism, or to test a hypothesis. Here, we evaluate and discuss model systems that were generated to understand clinical, pathological, genetic, biochemical, and epidemiological aspects of prion diseases. Whilst clinical research and studies on human tissue are an essential component of prion research, much of the understanding of the mechanisms governing transmission, replication, and toxicity comes from in vitro and in vivo studies. As with other neurodegenerative diseases caused by protein misfolding, the pathogenesis of prion disease is complex, full of conundra and contradictions. We will give here a historical overview of the use of models of prion disease, how they have evolved alongside the scientific questions, and how advancements in technologies have pushed the boundaries of our understanding of prion biology.

Genetic prion disease: Experience of a rapidly progressive dementia center in the United States and a review of the literature

Although prion diseases are generally thought to present as rapidly progressive dementias with survival of only a few months, the phenotypic spectrum for genetic prion diseases (gPrDs) is much broader. The majority have a rapid decline with short survival, but many patients with gPrDs present as slowly progressive ataxic or parkinsonian disorders with progression over a few to several years. A few very rare mutations even present as neuropsychiatric disorders, sometimes with systemic symptoms such as gastrointestinal disorders and neuropathy, progressing over years to decades. gPrDs are caused by mutations in the prion protein gene (PRNP), and have been historically classified based on their clinicopathological features as genetic Jakob-Creutzfeldt disease (gJCD), Gerstmann-Sträussler-Scheinker (GSS), or Fatal Familial Insomnia (FFI). Mutations in PRNP can be missense, nonsense, and octapeptide repeat insertions or a deletion, and present with diverse clinical features, sensitivities of ancillary testing, and neuropathological findings. We present the UCSF gPrD cohort, including 129 symptomatic patients referred to and/or seen at UCSF between 2001 and 2016, and compare the clinical features of the gPrDs from 22 mutations identified in our cohort with data from the literature, as well as perform a literature review on most other mutations not represented in our cohort. E200K is the most common mutation worldwide, is associated with gJCD, and was the most common in the UCSF cohort. Among the GSS-associated mutations, P102L is the most commonly reported and was also the most common at UCSF. We also had several octapeptide repeat insertions (OPRI), a rare nonsense mutation (Q160X), and three novel mutations (K194E, E200G, and A224V) in our UCSF cohort. © 2016 Wiley Periodicals, Inc.

Distinct effects of mutations on biophysical properties of human prion protein monomers and oligomers

Prion diseases are a group of fatal neurodegenerative illnesses, resulting from the conformational conversion of the cellular prion protein (PrP^C) into a misfolded form (PrP^Sc). The formation of neurotoxic soluble prion protein oligomer (PrP^O) is regarded as a key step in the development of prion diseases. About 10%-15% of human prion diseases are caused by mutations in the prion protein gene; however, the underlying molecular mechanisms remain unclear. In the present work, we compared the biophysical properties of wild-type (WT) human prion protein 91-231 (WT HuPrP_91-231) and its disease-associated variants (P105L, D178N, V203I, and Q212P) using several biophysical techniques. In comparison with WT HuPrP^C, the Q212P and D178N variants possessed greatly increased conversion propensities of PrP^C into PrP^O, while the V203I variant had dramatically decreased conversion propensity. The P105L variant displayed a similar conversion propensity to WT HuPrP^C Guanidine hydrochloride-induced unfolding experiments ranked the thermodynamic stabilities of these proteins as Q212P < D178N < WT ≈ P105L < V203I. It was thus suggested that the conversion propensities of the prion proteins are closely associated with their thermodynamic stabilities. Furthermore, structural comparison illustrated that Q212P, D178N, and V203I variants underwent larger structural changes compared with WT HuPrP^C, while the P105L variant adopted a similar structure to the WT HuPrP^C The mutation-induced structural perturbations might change the thermodynamic stabilities of the HuPrP^C variants, and correspondingly alter the conversion propensities for these prion proteins. Our results extend the mechanistic understanding of prion pathogenesis, and lay the basis for the prevention and treatment of prion diseases.

Activation of the unfolded protein response and granulovacuolar degeneration are not common features of human prion pathology

Human prion diseases are fatal neurodegenerative disorders with a genetic, sporadic or infectiously acquired aetiology. Neuropathologically, human prion diseases are characterized by deposition of misfolded prion protein and neuronal loss. In post-mortem brain tissue from patients with other neurodegenerative diseases characterized by protein misfolding, including Alzheimer’s disease (AD) and frontotemporal lobar degeneration with tau pathology (FTLD-tau), increased activation of the unfolded protein response (UPR) has been observed. The UPR is a cellular stress response that copes with the presence of misfolded proteins. Recent studies have indicated that UPR activation is also involved in experimental models of prion disease and have suggested intervention in the UPR as a therapeutic strategy. On the other hand, it was previously shown that the active form of the UPR stress sensor dsRNA-activated protein kinase-like ER kinase (PERK) is not increased in post-mortem brain tissue samples from human prion disease cases. In the present study, we assessed the active form of another UPR stress sensor, inositol-requiring enzyme 1α (IRE1α), in human post-mortem frontal cortex of a large cohort of sporadic, inherited and acquired prion disease patients (n = 47) and non-neurological controls. Immunoreactivity for phosphorylated IRE1α was not increased in prion disease cases compared with non-neurological controls. In addition, immunoreactivity for phosphorylated PERK was unaltered in human prion disease cases included in the current cohort. Moreover, no difference in the extent of granulovacuolar degeneration, a pathological feature associated with the presence of UPR activation markers, was detected. Our data indicate that, in contrast to AD and primary tauopathies, activation of the UPR is not a common feature of human prion pathology.

Hereditary Human Prion Diseases: an Update

Prion diseases in humans are neurodegenerative diseases which are caused by an accumulation of abnormal, misfolded cellular prion protein known as scrapie prion protein (PrP^Sc). Genetic, acquired, or spontaneous (sporadic) forms are known. Pathogenic mutations in the human prion protein gene (PRNP) have been identified in 10-15 % of CJD patients. These mutations may be single point mutations, STOP codon mutations, or insertions or deletions of octa-peptide repeats. Some non-coding mutations and new mutations in the PrP gene have been identified without clear evidence for their pathogenic significance. In the present review, we provide an updated overview of PRNP mutations, which have been documented in the literature until now, describe the change in the DNA, the family history, the pathogenicity, and the number of described cases, which has not been published in this complexity before. We also provide a description of each genetic prion disease type, present characteristic histopathological features, and the PrP^Sc isoform expression pattern of various familial/genetic prion diseases.

The Features of Genetic Prion Diseases Based on Chinese Surveillance Program

Objective

To identify the features of Chinese genetic prion diseases.

Methods

Suspected Creutzfeldt-Jakob disease (CJD) cases that were reported under CJD surveillance were diagnosed and subtyped using the diagnostic criteria issued by the WHO. The general information concerning the patient, their clinical, MRI and EEG data, and the results of CSF 14-3-3 and PRNP sequencing were carefully collected from the database of the national CJD surveillance program and analyzed using the SPSS 11.5 statistical software program.

Results

Since 2006, 69 patients were diagnosed with genetic prion diseases and as having 15 different mutations. The median age of the 69 patients at disease onset was 53.5 years, varying from 19 to 80 years. The majority of patients displaying clinical symptoms were in the 50–59 years of age. FFI, T188K gCJD and E200K were the three most common subtypes. The disease appeared in the family histories of 43.48% of the patients. The clinical manifestations varied considerably among the various diseases. Patients who carried mutations in the N-terminus displayed a younger age of onset, were CSF 14-3-3 negative, had a family history of the condition, and experienced a longer duration of the condition. The clinical courses of T188K were significantly shorter than those of FFI and E200K gCJD, while the symptoms in the FFI group appeared at a younger age and for a longer duration. Moreover, the time intervals between the initial neurologist visit to the final diagnosis were similar among patients with FFI, T188K gCJD, E200K gCJD and other diseases.

Conclusion

The features of Chinese genetic prion diseases are different from those seen in Europe and other Asian countries.

Genetic studies in human prion diseases

Human prion diseases are fatal neurodegenerative disorders that are characterized by spongiform changes, astrogliosis, and the accumulation of an abnormal prion protein (PrP(Sc)). Approximately 10%-15% of human prion diseases are familial variants that are caused by pathogenic mutations in the prion protein gene (PRNP). Point mutations or the insertions of one or more copies of a 24 bp repeat are associated with familial human prion diseases including familial Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker syndrome, and fatal familial insomnia. These mutations vary significantly in frequency between countries. Here, we compare the frequency of PRNP mutations between European countries and East Asians. Associations between single nucleotide polymorphisms (SNPs) of several candidate genes including PRNP and CJD have been reported. The SNP of PRNP at codon 129 has been shown to be associated with sporadic, iatrogenic, and variant CJD. The SNPs of several genes other than PRNP have been showed contradictory results. Case-control studies and genome-wide association studies have also been performed to identify candidate genes correlated with variant and/or sporadic CJD. This review provides a general overview of the genetic mutations and polymorphisms that have been analyzed in association with human prion diseases to date.

Small-molecule theranostic probes: a promising future in neurodegenerative diseases

Prion diseases are fatal neurodegenerative illnesses, which include Creutzfeldt-Jakob disease in humans and scrapie, chronic wasting disease, and bovine spongiform encephalopathy in animals. They are caused by unconventional infectious agents consisting primarily of misfolded, aggregated, β -sheet-rich isoforms, denoted prions, of the physiological cellular prion protein (PrP(C)). Many lines of evidence suggest that prions (PrP(Sc)) act both as a template for this conversion and as a neurotoxic agent causing neuronal dysfunction and cell death. As such, PrP(Sc) may be considered as both a neuropathological hallmark of the disease and a therapeutic target. Several diagnostic imaging probes have been developed to monitor cerebral amyloid lesions in patients with neurodegenerative disorders (such as Alzheimer's disease, Parkinson's disease, and prion disease). Examples of these probes are Congo red, thioflavin T, and their derivatives. We synthesized a series of styryl derivatives, denoted theranostics, and studied their therapeutic and/or diagnostic potentials. Here we review the salient traits of these small molecules that are able to detect and modulate aggregated forms of several proteins involved in protein misfolding diseases. We then highlight the importance of further studies for their practical implications in therapy and diagnostics.

Squirrel monkeys (Saimiri sciureus) infected with the agent of bovine spongiform encephalopathy develop tau pathology

Squirrel monkeys (Saimiri sciureus) were infected experimentally with the agent of classical bovine spongiform encephalopathy (BSE). Two to four years later, six of the monkeys developed alterations in interactive behaviour and cognition and other neurological signs typical of transmissible spongiform encephalopathy (TSE). At necropsy examination, the brains from all of the monkeys showed pathological changes similar to those described in variant Creutzfeldt-Jakob disease (vCJD) of man, except that the squirrel monkey brains contained no PrP-amyloid plaques typical of that disease. Constant neuropathological features included spongiform degeneration, gliosis, deposition of abnormal prion protein (PrP(TSE)) and many deposits of abnormally phosphorylated tau protein (p-Tau) in several areas of the cerebrum and cerebellum. Western blots showed large amounts of proteinase K-resistant prion protein in the central nervous system. The striking absence of PrP plaques (prominent in brains of cynomolgus macaques [Macaca fascicularis] with experimentally-induced BSE and vCJD and in human patients with vCJD) reinforces the conclusion that the host plays a major role in determining the neuropathology of TSEs. Results of this study suggest that p-Tau, found in the brains of all BSE-infected monkeys, might play a role in the pathogenesis of TSEs. Whether p-Tau contributes to development of disease or appears as a secondary change late in the course of illness remains to be determined.

Human prion diseases in the Netherlands (1998-2009): clinical, genetic and molecular aspects

Prion diseases are rare and fatal neurodegenerative disorders that can be sporadic, inherited or acquired by infection. Based on a national surveillance program in the Netherlands we describe here the clinical, neuropathological, genetic and molecular characteristics of 162 patients with neuropathologically confirmed prion disease over a 12-year period (1998–2009). Since 1998, there has been a relatively stable mortality of Creutzfeldt-Jakob disease (CJD) in the Netherlands, ranging from 0.63 to 1.53 per million inhabitants per annum. Genetic analysis of the codon 129 methionine/valine (M/V) polymorphism in all patients with sporadic CJD (sCJD) showed a trend for under-representation of VV cases (7.0%), compared with sCJD cohorts in other Western countries, whereas the MV genotype was relatively over-represented (22,4%). Combined PrP^Sc and histopathological typing identified all sCJD subtypes known to date, except for the VV1 subtype. In particular, a “pure" phenotype was demonstrated in 60.1% of patients, whereas a mixed phenotype was detected in 39.9% of all sCJD cases. The relative excess of MV cases was largely accounted for by a relatively high incidence of the MV 2K subtype. Genetic analysis of the prion protein gene (PRNP) was performed in 161 patients and showed a mutation in 9 of them (5.6%), including one FFI and four GSS cases. Iatrogenic CJD was a rare phenomenon (3.1%), mainly associated with dura mater grafts. Three patients were diagnosed with new variant CJD (1.9%) and one with variably protease-sensitive prionopathy (VPSPr). Post-mortem examination revealed an alternative diagnosis in 156 patients, most commonly Alzheimer's disease (21.2%) or vascular causes of dementia (19.9%). The mortality rates of sCJD in the Netherlands are similar to those in other European countries, whereas iatrogenic and genetic cases are relatively rare. The unusual incidence of the VV2 sCJD subtype compared to that reported to date in other Western countries deserves further investigation.